Hourly Global Aerosol Diagnostics from NASA MERRA-2 Reanalysis

MERRA-2 provides hourly, time-averaged assimilated aerosol diagnostics on a global 0.625 x 0.5 degree grid from 1980 to present. The NASA Global Modeling and Assimilation Office (GMAO) produces this data using the Goddard Earth Observing System Model version 5.12.4. It includes column mass density for components like black carbon, dust, sea salt, sulfate, and organic carbon, as well as aerosol optical thickness at 550 nm.

Use Cases

• Modeling long-term trends in black_carbon or sulfate column mass density to assess emission policy impacts.
• Correlating sea_salt surface mass concentration with meteorological events over ocean regions.
• Estimating ground-level PM2.5 concentrations by applying documented formulas to component mass densities.
• Analyzing spatiotemporal patterns of total aerosol optical thickness at 550 nm for climate forcing studies.
• Validating satellite-derived dust aerosol optical depth against the assimilated dust diagnostics.

Strengths

• Continuous global coverage from 1980 to present, updated with a latency of approximately 3 weeks.
• Provides multiple aerosol component diagnostics, including black carbon, dust, sea salt, sulfate, and organic carbon.
• Hourly temporal resolution and 0.625 x 0.5 degree spatial resolution for detailed analysis.

Limitations

• Data is model-assimilated, not direct observation, introducing inherent reanalysis uncertainty.
• Derived PM concentrations require application of external formulas, adding a processing step.
• The dataset undergoes reprocessing, creating filename discrepancies between original and reprocessed files.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO) via the Goddard Earth Observing System Model (GEOS).

Collection Method

Atmospheric reanalysis assimilation of satellite and observational data.

Time Range

1980 to present.

Freshness

Updated monthly with ~3 week latency.

Geography

Global coverage.